A power conversion device formed of a power semiconductor is used in extensive fields ranging from consumer equipment, such as a home air conditioner and a refrigerator, to industrial equipment such as an inverter and a servo controller.
A power semiconductor is mounted on a circuit board, such as a metal base substrate or a ceramics substrate, in terms of power consumption. One or a plurality of circuit elements, such as power semiconductors, is mounted on the circuit board, and a plastic case frame is bonded to the circuit board and is sealed with a silicone gel or an epoxy resin, thereby forming a power semiconductor module.
Meanwhile, in order to reduce manufacturing cost, there is also a full mold power semiconductor module formed by a transfer molding method (for example, refer to PTL 1).
Normally, a power conversion device, in which the heretofore described power semiconductor module is used as a main circuit, is formed of other power circuit and control circuit. The power circuit and control circuit comprises various kinds of parts, such as an IC, an LSI, a resistance, a capacitor, and a reactor, but normally, are mounted on a printed circuit board.
FIG. 6 is a sectional view showing one example of a structure of a heretofore known power conversion device. As shown in FIG. 6, a power semiconductor module 30 is mounted on a heatsink 31 via thermal grease in order to enhance heat releasability. Further, a printed circuit board 32 and a printed circuit board 33, on each of which electronic circuit parts are mounted, are disposed above the power semiconductor module 30, and the printed circuit boards 32 and 33 are joined by pins 34 or the like. Further, as shown in FIG. 6, the portion from the upper side of the printed circuit board 32 to the lateral side of the printed circuit boards 32 and 33 and power semiconductor module 30 is covered with a cover 35.
The power semiconductor module 30 shown in FIG. 6 comprises an insulating substrate 36, power semiconductor elements 37, wires 38, a case body 39, and a lid 40. As shown in FIG. 6, the power semiconductor elements 37 are mounted on the insulating substrate 36. The insulating substrate 36 has, for example, a configuration wherein an insulating layer 42 is formed on the front surface of a metal base 41, and circuit patterns 43 are formed on the front surface of the insulating layer 42. The insulating layer 42 is formed by solidifying, for example, an epoxy resin containing inorganic filler.
As shown in FIG. 6, in the power semiconductor elements 37, the rear surface electrode thereof is joined to the top of the circuit pattern of the insulating substrate 36. Also, in the power semiconductor elements 37, the front surface electrode thereof is electrically connected to the adjacent circuit pattern 43 via the wire 38. Furthermore, connection lead terminals 45 and 46 are joined to the circuit patterns 43 by soldering or the like.
Further, the power semiconductor module 30 and the printed circuit boards 32 and 33 are electrically connected via the connection lead terminals 45 and 46.